Field of the Invention
The invention generally relates to a wireless communication technology, and more particularly, to a wireless communication method for resolving the evaluation precedence index (EPI) conflict in an evolved packet system (EPS) bearer or packet data protocol (PDP) context without deleting this EPS bearer or PDP context.
Description of the Related Art
Wireless communication systems have been used widely to provide various telecommunication services such as telephony, video, data, messaging, and broadcast services. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmission power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency divisional multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on the municipal, national, regional, and even global level. An example of an emerging telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by the Third Generation Partnership Project (3GPP). It is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrums, and integrating better with other open standards using OFDMA on downlinks (DL), and SC-FDMA on uplinks (UL) and multiple-input multiple-output (MIMO) antenna technology.
When data packets are transmitted, Traffic flow template (TFT) defines rules for data service with a specific quality of service treatment between user equipment (UE) and network. Therefore, when EPS bearer or PDP context provides Quality of Service (QoS) for special service or application, TFT may define rules so that UE and network knows which data packet (or IP packet) should be sent on particular EPS bearer or PDP context. Each rule describing how data packet is transmitted (e.g. protocol type, IP type, destination IP address, etc.) can be known as packet filter. Every packet filter has a locally unique identifier called packet filter identifier used to identify each packet filters within the same EPS bearer or PDP context, and another globally unique identifier called evaluation precedence index (EPI) used to identify packet filters across EPS bearer or PDP context within a packet data network (PDN) connection. The data packet will be classified according to the packet filters. During data packet classification, packet filters among all EPS bearers or PDP contexts within the same PDN are ordered by evaluation precedence indexes, and each data packet will be mapped to an EPS bearer or PDP context when it matches a packet filter. FIG. 1 is a schematic diagram illustrating the relationship between the PDN connection, EPS bearer/PDP context, TFT and packet filters. As shown in FIG. 1 a plurality of PDN connections (e.g. PDN connection#1 and PDN connection#2) may be established, and each of the PDN connection may correspond to one or more EPS bearers or PDP contexts (e.g. EPS bearer/PDP context #1 and EPS bearer/PDP context #2), wherein one PDN connection may have an Access Point Name (APN), an IP address, etc. and each EPS bearer corresponds to an EPS Bearer Identity (EBI) and an Quality of Service (QoS), and each PDP context corresponds a Network Layer Service Access Point Identifier (NSAPI) and an Quality of Service (QoS). Each of the TFT may define packet filters so that UE and network knows which data packet (or IP packet) should be sent on particular EPS bearer or PDP context, wherein each packet filter may have an EPI and packet filter content (e.g. protocol type, IP type, destination IP address, etc.). The EPS bearer is applied to a 4G network and the EPS bearer may be a default EPS bearer or a dedicated EPS bearer. The PDP context is applied to a 2/3G network and the PDP context may be a primary PDP context or a secondary PDP context. A default EPS bearer (or primary PDP context) is assigned when a PDN connection is established. That is to say, the default EPS bearer will exist until the PDN connection is disconnected. A dedicated EPS bearer (or secondary PDP context) is assigned for a particular service or application, such as VoIP service, video service, etc.
In 3GPP standard, it defines that when UE encounters EPI conflict (i.e. new packet filter and old packet filter has the same EPI) during EPS bearer or PDP context activation or modification, it shall accept the new packet filter setting from network. Then, after EPS bearer or PDP context activation or modification completes, the EPS bearer or PDP context where the original packet filter belongs should be deactivated. However, when EPI conflict occurs within the same EPS bearer or PDP context, it would cause the new packet filter setting becomes useless, since the original and the new packet filter belongs to the same EPS bearer or PDP context. Namely, the UE will soon initiate an EPS bearer or PDP context deactivation procedure to delete the EPS bearer or PDP context, after EPS bearer or PDP context activation or modification has completed. Note that, the scenario above for “EPI conflict within same EPS bearer or PDP context” only takes place when new packet filter identifier differs from every existing packet filters; namely, if new packet filter identifier matches any existing packet filter, it should be treated as a normal replacement of that existing packet filter, and should not be considered as EPI conflict.
Taking FIGS. 2A-2B for example, FIG. 2A is a schematic diagram illustrating an EPI conflict in a default EPS bearer (or primary PDP context) and FIG. 2B is a schematic diagram illustrating an EPI conflict in a dedicated EPS bearer (or secondary PDP context). As shown in FIG. 2A, there are a default EPS bearer (or primary PDP context) and a dedicated EPS bearer (or secondary PDP context) corresponding to a packet data network (PDN) connection. When the network assigns a packet filter #2 (EPI=X) which corresponds to the default EPS bearer to the UE, the packet filter #2 (EPI=X) will conflict with the existing packet filter #1 (EPI=X) of the default EPS bearer. Therefore, the UE will initiate an EPS bearer deactivation procedure for the default EPS bearer to delete the default EPS bearer (i.e. the PDN connection will be disconnected) because the default EPS bearer corresponds to the old packet filter #1 (EPI=X). As shown in FIG. 2B, there are a default EPS bearer (or primary PDP context) and a dedicated EPS bearer (or secondary PDP context) corresponding to a packet data network (PDN) connection. When the network assigns a packet filter #2 (EPI=Y) which corresponds to the dedicated EPS bearer to the UE, the packet filter #2 (EPI=Y) will conflict with the existing packet filter #1 (EPI=Y) of the dedicated EPS bearer. Therefore, the UE will initiate an EPS bearer deactivation procedure for the dedicated EPS bearer to delete the dedicated EPS bearer because the dedicated EPS bearer corresponds to the old packet filter #1 (EPI=Y).
Therefore, it would lead to the unexpected early termination of the data service, and even disconnection of whole PDN connection, if it occurs within a default EPS bearer or primary PDP context.